Method for manufacturing an electronic device having an electronically determined physical test member

ABSTRACT

A method for manufacturing an electronic device such as an integrated circuit or display device is provided. A design description of the electronic device is generated using a computer aided design tool. Physical device data representing a physical description of the electronic device are electronically determined based on the design description. The physical device data includes data defining connection points for connecting the electronic device to external circuits and data identifying a plurality of connection points of the electronic device. A physical embodiment of the electronic device is produced in accordance with the physical device data. Physical test member data representing conductors and contact points of a test member for testing the electronic device are electronically determined. The test member is produced in accordance with the test member data and used to test the electronic device.

This is a continuation of U.S. patent application Ser. No. 10/641,567,filed Aug. 14, 2003, now U.S. Pat. No. 6,957,405, which was acontinuation of U.S. patent application Ser. No. 10/041,866, filed Jan.7, 2002, now U.S. Pat. No. 6,622,289, which was a continuation of U.S.patent application Ser. No. 09/154,410, filed Sep. 15, 1998, now U.S.Pat. No. 6,343,369.

BACKGROUND OF THE INVENTION

This invention relates to contact devices for making connection to anelectronic circuit device and to methods of fabricating and using such acontact device, such as in the manufacture of semiconductor, liquidcrystal displays or other devices, and improved contact devices.

An important aspect of the manufacture of integrated circuit chips isthe testing of the circuit embodied in the chip in order to verify thatit operates according to specifications. Although the circuit could betested after the chip has been packaged, the expense involved in dicingthe wafer and packaging the individual chips makes it preferable to testthe circuit as early as possible in the fabrication process, so thatunnecessary efforts will not be expended on faulty devices. It istherefore desirable that the circuits be tested either immediately afterwafer fabrication is completed, and before separation into dice, orafter dicing, but before packaging. In either case, it is necessary tomake electrical connection to the circuits' external connection points(usually bonding pads) in a non-destructive way, so as not to interferewith subsequent packaging and connection operations.

U.S. Pat. No. 5,221,895 discloses a probe for testing integratedcircuits. The probe includes a stiff metal substrate made of berylliumcopper alloy, for example. The substrate is generally triangular in formand has two edges that converge from a support area toward a generallyrectangular tip area. There is a layer of polyimide over one main faceof the substrate, and gold conductor runs are formed over the layer ofpolyimide. The conductor runs and the metal substrate form microstriptransmission lines. The conductor runs extend parallel to one anotherover the tip area and fan out toward the support area. A contact bump isdeposited on the end of each conductor run that is on the tip area. Thetip area of the substrate is slit between each two adjacent conductorruns whereby the tip area is divided into multiple separately flexiblefingers that project in cantilever fashion from the major portion of thesubstrate.

The probe shown in U.S. Pat. No. 5,221,895, is designed to be used in atest station. Such a test station may include four probes having theconfiguration shown in U.S. Pat. No. 5,221,895, the probes beingarranged in an approximately horizontal orientation with their contactbumps facing downwards, with the four rows of contact bumps along fouredges of a rectangle. The DUT is generally rectangular and hasconnection pads along the edges of one face. The DUT is placed in avacuum chuck with its connection pads upwards. The vacuum chuck drivesthe DUT upward into contact with the probe, and overdrives the DUT by apredetermined distance from first contact. According to current industrystandards, such a test station is designed to produce a nominal contactforce of 10 grams at each connection pad. Therefore, the amount of theoverdrive is calculated to be such that if contact is made at allconnection pads simultaneously, so that each contact bump is deflectedby the same amount, the total contact force will be 10 grams forcemultiplied by the number of connection pads.

If the material of the probe substrate is a beryllium copper alloy andeach flexible finger has a length of about 0.75 mm, a width of about 62microns and a height of about 250 microns, and the probe is supported sothat the mechanical ground is at the root of the fingers, the contactforce produced at the tip of the finger is about 7.7 grams for eachmicrometer of deflection of the tip of the finger. Therefore, if thecontact bumps at the tips of the fingers are coplanar and the connectionpads of the DUT are coplanar, and the plane of the contact bumps isparallel to the plane of the connection pads, an overdrive of about 1.3microns from first contact will result in the desired contact force of10 grams at each connection pad. However, if one of the connection padsshould be 1.3 microns farther from the plane of the contact bumps thanthe other connection pads, when the DUT is displaced by 1.3 microns fromfirst contact, there will be no contact force between this connectionpad and its contact bump, and all the contact force that is generatedwill be consumed by the other contacts. If one assumes that the contactforce at a connection pad must be at least 50 percent of the nominalcontact force in order for there to be a reliable connection, then themaximum variance from the nominal height that this design willaccommodate is +/−0.7 microns. However, the height variations of contactbumps and connection pads produced by the standard processes currentlyemployed in the semiconductor industry typically exceed 5 microns.

Furthermore, even if the contact bumps are coplanar and the connectionpads are coplanar, tolerances in the probing apparatus make itimpossible to ensure that the plane of the connection pads is parallelto the plane of the contact bumps, and, in order to accommodate thesetolerances, it is necessary to displace the DUT by 75 microns in orderto ensure contact at all connection pads. If the dimensions of thefinger were changed to accommodate a displacement of 70-80 microns (75microns +/−5 microns), the probe would become much less robust. If theprobe were supported at a location further back from the root of thefingers, such that most of the deflection would be carried by thesubstrate rather than the fingers, the ability of the fingers to conformwould be limited to 0.13 microns/gram deflection produced at the fingersthemselves.

The connection pads of the DUT are not coplanar, nor are the connectionbumps on the probe. Assuming that the nominal plane of the connectionpads (the plane for which the sum of the squares of the distances of thepads from the plane is a minimum) is parallel with the nominal plane ofthe contact bumps, the variation in distance between the connection padand the corresponding contact bump is up to 5 microns if both the DUTand the probe are of good quality.

At present, the connection points on an integrated circuit chip are at apitch of at least 150 microns, but it is expected that it will befeasible for the pitch to be reduced to about 100 microns within a fewyears.

As the need arises to make connection at ever finer pitches, the stressin a probe of the kind shown in U.S. Pat. No. 5,221,895 increases. Ifthe connection pads are at a spacing of 75 microns, this implies thatthe width of the fingers must be less than about 50 microns, and inorder to keep the stress below the yield point, the height of thefingers must be at least 400 microns.

The necessary height of the fingers can be reduced by employing a metalof which the yield point is higher than that of beryllium copper. Forexample, if the substrate is made of stainless steel, having an elasticmodulus of 207×10⁹ N/m², the maximum height of the fingers can bereduced to about 350 microns. However, it follows that the deflection isreduced below that necessary to comply with typical height variationsfound in the industry. Additionally, the resistivity of stainless steelis substantially higher than that of beryllium copper, and this limitsthe frequency of the signals that can be propagated by the microstriptransmission lines without unacceptable degradation. In general, priortechniques found limited application due to difficulties in achievingadequate deflection with the necessary force to achieve reliableconnection, while withstanding the generated stresses.

In addition, although the microstrip transmission line has adequatecharacteristics for signals up to a frequency of 5 GHz, and it has beendiscovered that the so-called stripline configuration is desirable forhigher frequencies.

U.S. Pat. No. 5,621,333 and PCT/US96/07359, both of which areincorporated herein by reference, disclose improvements and advancementsover what is described in U.S. Pat. No. 5,221,895. It has beendiscovered, however, that further improvements and advancements oversuch disclosures, particularly with respect to the manufacture andstructure and use of such contact devices or probes, is required to makecontact devices over probes for fine pitch and other integratedcircuits, liquid crystal displays and other electronic devices.

SUMMARY OF THE INVENTION

The present invention provides improvements and advancements over suchprior disclosures, particularly with respect to the manufacture andstructure and use of such contact devices or probes, is required to makecontact devices over probes for fine pitch and other integratedcircuits, liquid crystal displays and other electronic devices.

In accordance with a first aspect of such contact devices, there may beprovided a method of making a multilayer composite structure for use inmanufacture of a contact device for establishing electrical connectionto a circuit device, said method comprising providing a substrate of ametal having a resistivity substantially greater than about 10 micro-ohmcm, adhering a first layer of metal having a resistivity less than about3 micro-ohm cm to a main face of the substrate, the first layer having amain face that is remote from the substrate, adhering a second layer ofdielectric material to the main face of the first layer, the secondlayer having a main face that is remote from the substrate, and adheringa third layer of metal to the main face of the second layer, the metalof the third layer having a resistivity less than about 3 micro-ohm cm.

In accordance with another second aspect of such contact devices, theremayb be provided a method of making a contact device for use inestablishing electrical connection to a circuit device, said methodcomprising providing a substrate of a metal having a resistivitysubstantially greater than about 10 micro-ohm cm, the substrate having amajor portion and a tip portion projecting therefrom along an axis,adhering a first layer of metal having a resistivity less than about 3micro-ohm cm to a main face of the substrate, the first layer having amain face that is remote from the substrate, adhering a second layer ofdielectric material to the main face of the first layer, the secondlayer having a main face that is remote from the substrate, adhering athird layer of metal to the main face of the second layer, the metal ofthe third layer having a resistivity less than about 3 micro-ohm cm,selectively removing metal of the third layer to form discrete conductorruns extending over the tip portion parallel to said axis, while leavingportions of the second layer exposed between the conductor runs, wherebya multi-layer composite structure is formed, and slitting the tipportion of the composite structure parallel to said axis, wherebyfingers are formed that project from the major portion of the compositestructure in cantilever fashion and each of which supports at least oneconductor run.

In accordance with another aspect of such contact devices, there may beprovided a probe apparatus for use in testing an integrated circuitembodied in an integrated circuit chip, said probe apparatus comprisinga support member having a generally planar datum surface, a generallyplanar elastic probe member having a proximal end and a distal end, atleast one attachment member attaching the probe member at its proximalend to the support member with the probe member in contact with thedatum surface, at least one adjustment member effective between thesupport member and a location on the probe member that is between theproximal and distal ends thereof for urging the distal end of the probemember away from the support member, whereby the probe member undergoeselastic deflection.

In accordance with another aspect of such contact devices, there may beprovided a probe apparatus for use in testing an integrated circuitembodied in an integrated circuit chip, said probe apparatus comprisinga support member having a bearing surface, a probe member having aproximal end and a distal end and comprising a stiff substrate havingfirst and second opposite main faces and conductor runs extending overthe first main face of the substrate from the distal end of thesubstrate to the proximal end thereof, the conductor runs of the probemember being distributed over a connection region of the first main faceof the substrate in a first predetermined pattern, at least oneattachment member attaching the probe member to the support member withthe second main face of the probe member confronting the bearing surfaceof the support member, a circuit board comprising a substrate having amain face and conductor runs distributed over a connection region ofsaid main face of the circuit board in a second predetermined pattern, aflexible circuit comprising a flexible substrate having a main face andfirst and second connection regions, and conductor runs extendingbetween the first and second connection regions of the flexiblesubstrate and distributed over the first connection region in a patterncorresponding to said first pattern and distributed over the secondconnection region in a pattern corresponding to said second pattern, afirst attachment device attaching the flexible circuit to the supportmember with the first connection region of the flexible circuitconfronting the connection region of the probe member and the conductorruns of the flexible circuit in electrically conductive connection withrespective conductor runs of the probe member, and a second attachmentdevice attaching the flexible circuit to the circuit board with thesecond connection region of the flexible circuit confronting theconnection region of the circuit board and the conductor runs of theflexible circuit in electrically conductive connection with respectiveconductor runs of the circuit board.

In accordance with another aspect of such contact devices, there may beprovided a method of making a multilayer composite structure for use inmanufacture of a contact device for establishing electrical connectionto a circuit device, said method comprising providing a substrate,adhering a first layer of dielectric material to a main face of thesubstrate, the first layer having a main face that is remote from thesubstrate, and adhering a second layer of metal to the main face of thefirst layer, the metal of the second layer having a resistivity lessthan about 3 micro-ohm cm.

In accordance with another aspect of such contact devices, there may beprovided a method of making a contact device for use in establishingelectrical connection to a circuit device, said method comprisingproviding a substrate having a major portion and a tip portionprojecting therefrom along an axis, adhering a first layer of dielectricmaterial to the main face of the substrate, the first layer having amain face that is remote from the substrate, adhering a second layer ofmetal to the main face of the first layer, the metal of the second layerhaving a resistivity less than about 3 micro-ohm cm, selectivelyremoving metal of the second layer to form discrete conductor runsextending over the tip portion parallel to said axis, while leavingportions of the first layer exposed between the conductor runs, wherebya multilayer composite structure is formed, and slitting the tip portionof the composite structure parallel to said axis, whereby fingers areformed that project from the major portion of the composite structure incantilever fashion and each of which supports at least one conductorrun.

In accordance with another aspect of such contact devices, there may beprovided a contact device having a plurality of nominally coplanar firstcontact elements for making electrical contact with correspondingnominally coplanar second contact elements of an electronic device bypositioning the contact device and the electronic device so that theplane of the first contact elements is substantially parallel to theplane of the second contact elements and effecting relative displacementof the devices in a direction substantially perpendicular to the planeof the first contact elements and the plane of the second contactelements to generate a contact force of at least f at each pair ofcorresponding first and second contact elements, wherein it is necessaryto effect relative displacement of the devices by a distance d in saiddirection from first touchdown to last touchdown, said contact devicecomprising a stiff substrate having a major portion with fingersprojecting therefrom in cantilever fashion, each finger having aproximal end at which it is connected to the major portion of thesubstrate and an opposite distal end and there being at least one, andno more than two, contact elements on the distal end of each finger, asupport member to which the substrate is attached in a manner such thaton applying force in said direction to the distal ends of the fingers,deflection occurs both in the fingers and in the major portion of thesubstrate, and means for effecting relative movement of the devices insaid direction, and wherein the substrate is dimensioned such thatrelative displacement of the devices in said direction by a distance dfrom first touchdown generates a reaction force at each contact elementof about 0.1*f+/−0.1*f, and further relative displacement of the devicesin said direction by a distance of about 75 micron or 5*d beyond lasttouchdown generates a reaction force at each contact element of about0.9*f +/−0.1*f.

In accordance with another aspect of such contact devices, there may beprovided a method for testing/manufacturing devices such as integratedcircuits or displays (such as LCD panels), which may include the stepsof carrying out a manufacturing process for the DUT, such as aplanar-type integrated circuit manufacturing process, positioning theDUT on a positioning device, such as a vacuum chuck (the DUT may be inwafer or die form, in the case of integrated circuits, etc.), effectingalignment of a contact device in accordance with the present inventionwith the DUT to the extent required for proper placement, effectingrelative movement of the DUT with respect to the contact device toestablish initial contact thereto (as determined electrically or by amechanical means), over-driving the relative movement to establishreliable electrical connection, wherein stresses are desirably sharedbetween the extended fingers of the contact device and the substrate ofthe contact device, applying test signals to the DUT and determiningwhether the DUT is defective or otherwise within or outside acceptablespecifications, recording whether the pass/fail condition of the DUT(which may include mechanical notation, such as inking the DUT ifdefective, etc., or by data recording), removing the DUT from thepositioning device, and packaging and assembling the DUT if acceptable.

With the present invention, devices with connection points of fine pitchmay be reliably tested and manufactured, and in particular improvedcontact devices, improved methods of making contact devices, andimproved methods of producing electronic devices may be obtained inaccordance with various preferred embodiments and aspects as describedelsewhere herein.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same maybe carried into effect, reference will now be made, by way of example,to the accompanying drawings in which:

FIGS. 1-5 illustrate various steps during fabrication of a contactdevice that may embody the present invention, FIGS. 1 and 4 being planviews and FIGS. 2, 3 and 5 being sectional views;

FIG. 6 is a partial perspective view of a contact device that may embodythe invention;

FIG. 6A is a sectional view on the line VIA-VIA of FIG. 6;

FIG. 7 is a general view, partly in section, of a semiconductor tester;

FIG. 8 is a plan view of a circuit board and mounting plate that formpart of the test head of the tester shown in FIG. 7;

FIG. 9 is an enlarged perspective view of the mounting plate and alsoillustrates back-up blocks that are attached to the mounting plate;

FIGS. 9A, 9B, and 9C are sectional views illustrating the manner inwhich the back-up blocks are attached to the mounting plate;

FIG. 10 is an enlarged view of a flexible circuit that is used toconnect the circuit board to the contact device;

FIGS. 11A and 11B are sectional views illustrating the manner in whichthe contact device and the flexible circuit are positioned relative tothe mounting block;

FIGS. 12A and 12B are sectional views illustrating the manner in whichthe mounting plate and the flexible circuit are positioned relative tothe circuit board

FIG. 13 illustrates a substrate with four exemplary probe members forpurposes of explaining preferred embodiments of fabrication processes inaccordance with the present invention;

FIG. 14 is a diagram illustrated a chuck used in fabricating contactdevices in accordance with preferred embodiments of the presentinvention;

FIGS. 15A and 15B are diagrams illustrated laser cutting of contactdevices in accordance with preferred embodiments of the presentinvention;

FIG. 16 is a diagram illustrating an embodiment of the present inventionin which dynamic adjustment of the probe member in relation to a focusedlaser beam is provided;

FIGS. 17 and 18 illustrate probe members fabricated in accordance withalternate preferred embodiments utilizing a two phase type laser cuttingprocess;

FIG. 19 illustrates contact points or pads of an electronic device inaccordance with alternative embodiments of the present invention;

FIGS. 20 to 22 illustrate electronic devices and probe members having orutilizing probe members with multiple contacts per finger;

FIG. 23 is a diagram illustrating a portion of a probe member having acontrolled impedance region and a stubb region;

FIGS. 24A to 24C illustrate improved contact devices in which moreuniform scrub characteristics may be obtained;

FIGS. 25A to 25D illustrates fingers of a probe having multiple contactsper finger and partial compliance slits formed in a back side of thefinger;

FIGS. 26A and 26B are diagrams illustrating an improved electronicdevice and contact design flow in accordance with certain preferredembodiments of the present invention;

FIGS. 27 and 28 illustrate a configuration of probe members to produce acontact device for probing multiple electronic devices or an array ofcontacts, and an exemplary use of such a contact device; and

FIG. 29 illustrates a probe member having external components orimpedances formed on the probe member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The context for the present invention will be by way of the disclosurein U.S. Pat. No. 5,621,333 and PCT/US96/07359, which are incorporatedherein by reference. Thereafter, improvements and advancements over suchdisclosures in accordance with the present invention, particularly withrespect to the manufacture and structure of such contact devices orprobes, will be described. It is understood that methods and structuremay be used for testing fine pitch and other integrated circuits, liquidcrystal displays and other electronic devices.

FIG. 1 illustrates a substrate 4 of elastic metal having an upper mainface 6 and a lower main face. In a preferred embodiment of theinvention, the substrate is stainless steel and is about 125 micronsthick. The substrate is generally triangular in form, having two edges 8that converge from a support area 10 toward a generally rectangular tiparea 12. The substrate is substantially mirror-image symmetrical about acentral axis 18.

Referring to FIG. 2, a thin film 14 of gold is deposited on the uppermain face 6 of the substrate 4 by evaporation or sputtering. The goldfilm may be augmented by plating if desired. An insulating material suchas polyimide is spun or sprayed onto the upper main face of the film 14in the liquid phase and is then cured to form a layer 16 about 25microns thick.

A layer 20 of gold is deposited over the upper main face 22 of the layer16 by evaporation or sputtering. The layer 20 is patterned usingconventional photolithographic techniques to form strips 26 that extendparallel to the central axis 18 over the tip area 12 of the probe andfan out from the tip area over the triangular part of the substrate 4toward the support area 10 but which may be connected together at thesupport area. Each strip has a proximal end and a distal end relative tothe support area 10. Additional metal is then deposited over the stripsby plating. After the strips have been built up to the desiredthickness, which may be about 12 microns, a layer 30 of photomaskmaterial (FIG. 5) is deposited over the upper surface of the structureshown in FIGS. 3 and 4 and holes 32 are formed in that layer over thedistal end of each strip 26, as shown in portion (a) of FIG. 5. A hardcontact metal, such as nickel, is deposited into these holes (FIG. 5,portion (b)) by plating, and the photomask material is then removed(FIG. 5, portion (c)). The connections between the strips are removed byetching. In this manner, separate conductor runs are formed over thelayer 16, and each conductor run has a contact bump 34 over its distalend. The conductor runs are 50 microns wide and are at a spacing betweencenters of about 125 over the tip area.

Referring to FIG. 6, a cover layer 40 of polyimide is formed over theconductor runs 26, over a region of the substrate that is to the rear,i.e. toward the support area 10, of the rectangular tip area 12 and alayer 44 of gold is deposited over the layer 40 by evaporation orsputtering. The layer 44 may be augmented by plating. The result of thefabrication steps described above is a multilayer structure thatcomprises the substrate 4, the gold film 14, the polyimide layer 16, thegold conductor runs 26, the polyimide layer 40, and the gold layer 44.

The tip area of the multilayer structure is then slit, whereby the tiparea is divided into multiple separately flexible fingers 48 thatproject in cantilever fashion from the major portion of the structure. Agiven finger of the substrate may carry the distal end portion of asingle conductor run, or it may carry the distal end portions of twoadjacent conductor runs. The slitting of the tip area may be performedby ablation using a ultraviolet laser. The poor thermal conductivity ofstainless steel is a favorable factor with regard to the laser ablationprocess. The width of the kerf that is removed is about 17 microns, sothat the width of a finger is either about 108 microns or about 233microns. The length of each finger is about 1 mm.

The structure shown in FIG. 6 may be used as a contact device for makingelectrical connection to contact pads of an electrical circuit device,such as an integrated circuit chip or a flat panel display device. Thenickel bumps 34 serve as probe elements for contacting the connectionpads of the circuit device. When the contact device is in use, eachnickel bump contacts a single connection pad of the circuit device. Abump 34 a that is to contact a ground pad of the circuit device may beconnected to the substrate by means of vias 46 formed in holes in thelayer 16 before depositing the layer 20. Multiple vias 46 may beprovided along the length of the conductor run 26 that ends at the bump34 a in order to ensure that the contact bump 34 a is firmly grounded.

The configuration of the conductor runs and their spacing results inthere being a stripline transmission line environment to the rear of theforward boundary of the layer 44, whereas there is a microstriptransmission line environment forward of the layer 44. Naturally, theslitting of the tip area results in degradation of the microstriptransmission line environment. In the case of the fingers being about 1mm long, the microstrip transmission line environment extends to a pointthat is about 2 mm from the contact bumps. However the degradation isnot so severe as to distort signals at frequencies below about 10 GHz toan unacceptable degree.

The structure shown in FIG. 6 may be used for probing a circuit devicein a semiconductor tester, as will be described with reference to FIGS.7-11.

Referring to FIG. 7, the tester comprises a prober 102 having a frame102 a that serves as a mechanical ground. A device positioner 104 havinga vacuum chuck 106 is mounted within or as part of the prober 102. Theprober includes stepping motors (not shown) that act on the devicepositioner for translating the vacuum chuck relative to the frame 102 ain two perpendicular horizontal directions (X and Y) and vertically (Z),and for rotating the vacuum chuck about a vertical axis. The vacuumchuck holds a device under test, or DUT, 108. FIG. 7 illustrates the DUT108 as a die that has previously been separated from other dice of thewafer in which it was fabricated, but it will be appreciated that, withappropriate modifications, the apparatus could be used for testing asemiconductor device at the wafer stage. As shown in FIG. 7, the DUT 108has contact pads 112.

The tester also comprises a test head 116 that can be docked to theprober so that it is in a reliably reproducible position relative to theprober frame 102 a. The test head 116 includes an essentially rigidcircuit board 122 (FIG. 8) that comprises an insulating substrate andconductor runs 126 exposed at the lower main face of the substrate. Vias(not shown) extend through the substrate and terminate at contact pads128 that are exposed at the upper main face of the substrate. Thecircuit board 122 is removably held in the test head by screws that passthrough holes 130 in the circuit board. When the test head 116 is dockedin the prober 102 and the circuit board 122 is installed in the testhead, the circuit board 122 is disposed horizontally and the contactpads 128 engage pogo pins 132, shown schematically in FIG. 7, by whichthe contact pads of the circuit board are connected to stimulus andresponse instruments (not shown), for purposes of conducting appropriatetests on the DUT.

A mounting plate 136 is secured to the circuit board 122. The mountingplate is positioned relative to the circuit board by guide pins 134 thatproject downward from the mounting plate and enter corresponding holesin the circuit board. The manner in which the mounting plate is attachedto the circuit board will be described below.

The mounting plate has a generally cylindrical exterior surface of whichthe central axis 138 is considered to be the axis of the plate. Theplate 136 is disposed with its axis 138 vertical and defines across-shaped through opening (FIG. 9) that is mirror image symmetricalabout X-Z and Y-Z planes that intersect at the axis 138. At the outerend of each limb of the cross, the plate 136 is formed with a notch 140that extends only part way through the plate and is bounded in thevertically downward direction by a horizontal surface 142.

A backup block 146 having the general shape, when viewed in plan, of atrapezoid seated on a rectangular base is positioned with itsrectangular base in one of the notches 140. Similar backup blocks 148are mounted in the other notches. The following description of thebackup block 146 and associated components applies equally to the backupblocks 148.

The rectangular base of the backup block 146 has a planar mountingsurface 150 (FIG. 7) that can be seated against the horizontal surface142 at the bottom of the notch 140. For assembling the backup block 146to the mounting plate 136, the backup block is formed with a hole 152extruding through its rectangular base, and the mounting plate is formedwith a blind hole 156 that is parallel to the axis of the mounting plateand enters the plate 136 at the horizontal surface 142. A guide pin 160is inserted through the hole 152 in the backup block and into the blindhole 156 in the mounting plate, and in this manner the backup block ispositioned with a moderate degree of precision relative to the mountingplate.

The backup block 146 is then attached to the mounting plate 136 by avertical locking screw 164 (FIG. 8, FIG. 9A) that passes through aclearance hole 168 in the backup block 146 and enters a threaded bore172 in the mounting plate 136 and a horizontal locking screw 176 (FIG.7) that passes through a clearance hole 180 in the mounting plate andenters a threaded bore 184 in the backup block. The backup block 146 isthereby attached to the mounting plate, and the guide pin 160 is thenremoved. The clearance holes 168 and 180 allow a small degree ofhorizontal and vertical movement of the backup block relative to themounting plate.

Two horizontal screws 186, which are horizontally spaced and disposedone on each side of the screw 176, are inserted through threaded holesin the peripheral wall of the plate 136 and enter blind clearance holesin the backup block. Similarly, two vertical screws 190, which arehorizontally spaced and disposed one on each side of the screw 164, areinserted through threaded holes in the backup block 146 and engage thesurface 142 of the mounting plate 136. The screws 176 and 186 can beused to adjust the horizontal position of the backup block relative tothe mounting plate 136. By selectively turning the screws 176 and 186,the backup block can be advanced or retracted linearly and/or rotatedabout a vertical axis. In similar fashion, using screws 164 and 190, thebackup block can be raised or lowered relative to the mounting plateand/or tilted about a horizontal axis. When the backup block is in thedesired position and orientation, the locking screws are tightened.

The apparatus shown in FIGS. 7-10 also comprises a contact device 194associated with the backup block 146. The contact device 194 isgenerally triangular and has two edges that converge from a support areatoward a generally rectangular tip area. The tip area of the contactdevice is divided into multiple fingers that extend parallel to an axisof symmetry of the contact device. The contact device includes conductorruns that extend from the support area to the tip area, and one runextends along each finger in the tip area. At its support area, theconductor runs of the contact device are exposed on the underside of thecontact device. The contact device may be fabricated by the method thatis described above with reference to FIGS. 1-6.

Inboard of the rectangular base, the trapezoidal portion of the backupblock 146 extends downward toward the central axis 138. The contactdevice 194 is disposed below the inclined lower surface of the backupblock 146 and is positioned relative to the backup block by guide pins202 (e.g., FIGS. 11A and 11B) that project from the backup block andpass through alignment holes 204 in the contact device. The manner inwhich the contact device is attached to the backup block will bedescribed below.

The apparatus also comprises a flexible circuit 208 having an inner edgeregion 208A and an outer edge region 208B (e.g., FIG. 10). The flexiblecircuit comprises a substrate of polyimide or similar insulatingmaterial, a ground plane (not shown) on the lower side of the substrate,and multiple discrete conductor runs 210 on the upper side of thesubstrate. Over the inner edge region 208A, the spacing of the conductorruns 210 corresponds to the spacing of the conductor runs across thesupport area of the contact device 194, and over the outer edge region208B, the spacing of the conductor runs 210 corresponds to the spacingof the conductor runs 126 along the inner edge of the printed circuitboard 122.

The flexible circuit is formed with inner and outer pairs of alignmentholes 214A and 214B. The inner pair of alignment holes 214A are threadedby the guide pins 202, whereby the inner edge region 208A is positionedrelative to the contact device 194. Similarly, the outer pair ofalignment holes 214B are threaded by the guide pins 134, whereby theouter edge region 208B of the flexible circuit is positioned relative tothe printed circuit board. The flexible circuit is also formed with twosets of mounting holes 218A and 218B.

The support area of the contact device 194, the inner edge region 208Aof the flexible circuit, and a first length 222A of Shinetsu strip areclamped between the backup block and a clamping plate 226A by means ofscrews 230A. The outer edge region 208B of the flexible circuit 208, theinner region of the printed circuit board 122, and a second length 222Bof Shinetsu strip are clamped between the mounting plate 136 and asecond clamping plate 226B by means of screws 230B. The positions of thealignment holes 214A and 214B relative to the conductor runs of theflexible circuit are such that the conductor runs 210 at the inner edgeregion 208A of the flexible circuit are in registration with theconductor runs 26 in the support area of the contact device, and theconductor runs 210 in the outer edge region 208B of the flexible circuitare in registration with the conductor runs 126 along the inner edge ofthe printed circuit board. The Shinetsu strip, the thickness of which isexaggerated in FIG. 7, is characterized by anisotropic electricalconductivity when compressed perpendicular to its length: itsconductivity is very good in directions perpendicular to its own planeand is very bad in directions parallel to its own plane and to itslength. Thus, the Shinetsu strip 222A connects the conductor runs 26 ofthe probe member 194 to respective conductor runs 210 of the flexiblecircuit 208, and the Shinetsu strip 222B connects the conductor runs 210of the flexible circuit 208 to respective conductor runs 126 of theprinted circuit board 122.

Tightening of the clamping screws compresses the Shinetsu strips, whichthen establish a good electrically conductive connection between theconductor runs of the contact device and the conductor runs 126 of theprinted circuit board 122, through the Shinetsu strips and respectiveconductor runs of the flexible circuit 208.

As described with reference to FIGS. 1-6, the tip area of the contactdevice 194 is divided into fingers, each of which has a contact run thatterminates in a contact bump. Since the tip area is spaced from thesupport area, at which the contact device is clamped to the backupblock, the tip area can be deflected away from the plane of theunderside of the backup block. Vertical adjustment screws 234 are fittedin respective threaded holes in the backup block 146. By appropriateadjustment of the screws 234, the contact device can be preloaded to acondition in which the contact device 194 is deflected downwardsrelative to the backup block 146, and by further adjustment of thescrews 234 the tip area can be forced downward, or permitted to rise, ortilted about the axis 18. It is important to note that the “mechanicalground” therefore extends to a location of the contact device that isbeyond the support area but does not extend as far as the lip area. Asdescribed more fully below, proper positioning of mechanical ground canenable stress sharing between the fingers of the contact device and thecontact device substrate, thereby enabling the contact device towithstand the stresses that result from applying force sufficient toensure reliable contact between the DUT and the contact device, giventhe irregularities that can be expected in actual devices/conditions.

When all four backup blocks are properly installed in the mounting plate136, the tip portions of the four contact devices extend along fouredges of a square and are positioned for making electrically conductivecontact to the contact pads of the device under test. By observing theDUT through the opening defined between the inner ends of the fourbackup blocks, the DUT can be positioned for contacting the contactbumps when the DUT is raised by the positioning device.

When the DUT is raised relative to the test head, the contact pads ofthe DUT engage the contact bumps of the contact device. After initialcontact has been established (first touchdown), the DUT is raised aninitial 10-15 microns, which is sufficient to absorb any expected errorin coplanarity of the contact bumps and contact pads and achieve lasttouchdown (each contact bump is in contact with its respective contactpad). The DUT is then raised by a further 75 microns. The spring rate ofthe fingers and the spring rate of the base region of the substrate,between the fingers and the support area, are such that the contactforce exerted at each contact pad is at least 10 grams. The initialdeflection of 10-15 microns is sufficient to provide a contact force ofabout 2 grams at a single finger, whereas the further deflection of 75microns provides a contact force of N*10 grams, where N is the number offingers, or 10 grams per finger. By sharing the deflection between thefingers and the base region of the substrate, a high degree ofcompliance may be achieved, allowing contact with all the contact bumps,without sacrificing the contact force that is needed to achieve areliable electrical contact between the contact bumps and the fingers.

The elastic nature of the metal of the substrate ensures that when theDUT is brought into contact with the contact bumps, and is slightly overdriven, deflection of the fingers provides a desirable scrubbing actionand also supplies sufficient contact force for providing a reliablepressure contact between the contact bump and the connection pad of theDUT.

The film 14 of gold may serve as the ground plane, and the substrate 4,although conductive, may not contribute to the electrical performance ofthe device, although this depends on the thickness and constituentmaterial of the substrate. In alternative embodiments, for example, thesubstrate is of sufficient thickness so that it provides sufficientconductivity to serve as the ground plane, or may consist of berylliumcopper, and thereby provide sufficient thickness to serve as the groundplane, with or without gold film 14.

It is should be particularly emphasized how the present inventionachieves desirous stress load sharing between the fingers and thesubstrate. It has been determined that with available materials, to beof practical size and provide suitable compliance/deflection of thefingers (such as to accommodate deviations from coplanarity, etc.),stress loads induced in the fingers and the substrate should be balanced(i.e., maintained in an acceptable relative range, below the stresslimit of the material). Proper positioning of a mechanical groundbetween the ends of the fingers and the back extremity of the supportarea can enable controlled balancing of the relative stress loads, whilealso ensuring an adequate deflection of the fingers to achieve adequatecompliance. In preferred embodiments, the relative stress loads of thefingers and substrate are maintained/balanced in a ranges of about 0.7to 1.3, 0.8 to 1.2 or 0.9 to 1.1. Other ranges may be utilized, providedthat a desirable balance is maintained, while of meeting the conditionsof adequate deflection/compliance in the fingers, while staying withinthe stress limits of the constant materials.

In combination with the stress load balancing, it also has beendiscovered that, with available materials, the length of the fingers,controlled by the length of the slit and overall physical geometry,etc., can be chosen to give the desired finger deflection/compliance,such as a desired deflection of greater than about 5 microns, 10microns, 12, microns or 15 microns, in the case of, for example, 60-80or 75 microns, etc., of overdrive, while maintaining stress balancing asdescribed above, which can produce a probe element that producesreliable connection with the DUT while surviving the resulting stressloads, etc.

The present invention may be desirably applied to the testing andmanufacture of devices such as integrated circuits or displays (such asLCD panels). Initially, a manufacturing process for the DUT 108 isconducted, such as a planar-type integrated circuit manufacturingprocess. For display devices, an appropriate LCD or other manufacturingprocess is conducted. After such manufacturing, the DUT 108 ispositioned on a positioning device, such as vacuum chuck 106 of prober102 (the DUT may be in wafer or die form, in the case of integratedcircuits, etc.). The DUT 108 is aligned with contact device 194 to theextent required for proper placement. Thereafter, relative movement iseffected of the DUT 108 with respect to the contact device 194 toestablish initial contact therebetween (as determined electrically or bya known mechanical means). After initial contact, over-driving of therelative movement to a predetermined degree is conducted (such asdescribed above) to establish reliable electrical connection, whereinstresses are desirably shared between the extended fingers of thecontact device and the substrate of the contact device. Positioning of amechanical ground as in the present invention is particularly desirousin this regard. Thereafter, test signals are applied to the DUT 108 andit is electrically determined whether the DUT is defective or otherwisewithin or outside acceptable specifications. The pass/fail condition ofthe DUT may be recorded (which may include mechanical notation, such asinking the DUT if defective, etc., or by data recording). Stillthereafter, the DUT 108 may be removed from the positioning device. Ifthe device is acceptable, known packaging and assembling of the DUT maybe performed.

With the present invention, devices with connection points of fine pitchmay be reliably tested and manufactured.

Conventional laser or other cutting of contact devices such as disclosedin U.S. Pat. No. 5,621,333, however, have been determined to beinadequate for fine pitch or otherwise more optimal contact devices. Thepresent invention particularly provides improved methods for producingsuch contact devices.

An important process in the formation of the contact device is cutting,preferably with a laser, fingers in the contact structure.(see. e.g.,FIG. 6). In accordance with preferred embodiments of the presentinvention, improved laser cutting processes are provided, which will nowbe described with reference to FIGS. 13 to 15. With such improvedmethods and implements to be hereinafter described, improved lasercutting of probe members in accordance with the present invention may beachieved.

FIG. 13 illustrates substrate or wafer 300, having alignment flat 302,on which is patterned (in this illustrative embodiment) four quadrantsof probe members 310 of a contact device. Some contact devices may, forexample, only use two rows of contacts, and thus only two portions needbe cut for a complete probe. In such embodiments, four probe members 310could be included on substrate 300 and cutting performed so as toproduce two complete contact devices. The number of probe members percontact device, and the numbers of probe members per substrate, may varydepending upon the particular application, although four quadrant probemembers 310 are illustrated for a conventional four sided integratedcircuit or display, etc. Substrate 300 also preferably includes guidepin holes 308 and fiducials 304 (fiducials 304 are to be cut with thelaser, as will be described hereinafter). Substrate 300 also preferablyincludes fiducials 305, which are preferably formed as part of thephotolithography steps that are used to produce substrate 300, and whichserve to provide a known positional reference for substrate 300 (andprobe members 310) for the laser positional and motion system. It alsoshould be noted that probe members 310 are shown with outline 314. Inpreferred embodiments, outline 314 is not provided as part of thephotolithographic or other processes that produce substrate 300, butinstead are provided by cutting of the laser. For illustrative purposes,outlines 314 are shown in FIG. 13.

Substrate 300 is cut by being fixedly positioned on chuck 332,illustrated in FIG. 14. Probe members 310 align on islands 336 of chuck332, the areas to be laser cut being positioned over openings, groovesor indentations 326. Chuck 332 is machined or tooled so that all lasercuts are over indentations 326 in order for laser cutting debris ordross to exit. Islands 336 of chuck 332 are provided with separatevacuum pull down hole 336 and vacuum grooves 322 in order to providepull down on probe member 310 at points near where laser cutting is tobe performed. It has been discovered that peripheral vacuum pull downonly does not enable fine slits to be cut as may be achieved with thepreferred embodiment of chuck 332.

It also should be noted that chuck 332 includes alignment flat 340, aplurality of peripheral vacuum holes 324 connecting to manifold 334,which is formed in the interior of chuck 332 and provides “plumbing” toroute the vacuum to the peripheral vacuum holes 324 and island vacuumholes 336, etc. Chuck 332 also preferably includes indentation 320,which serves to enable wafer 300 to be picked up from chuck 332 withconventional wafer tongs or the like. Chuck 332 also includes guide pincutting holes 328 and guide pin holes 330. It should be noted that guidepin cutting holes 328 are larger than guide pin holes 330. One guide pincutting hole 328 is positioned next to a guide pin hole 330, with twosuch pairs illustrated for illustrative purposes (more than two guidepin cutting holes and more than two guide pin holes could be provided;e.g., three pairs or four pairs of such holes, etc.). Each guide pincutting hole is shifted in the same direction, e.g., left or right (leftin FIG. 14), from the corresponding guide pin hole. As will be explainedlater, such a consistent shifting enables holes for guide pins to bemore efficiently formed in substrate 300.

It also should be noted that chuck 332 may be formed of two pieces, therectangular base portion, and the rounded top portion. The base portioncould be formed in a manner to be common to a variety of top portions,while particular top portions may be produced to be used with one ormore than one particular probe members to be laser cut. With such a twopiece chuck, the rectangular base portion may be used for more than topportion, thereby obviating the need for machining of the base portionfor each top portion. A particular top portion may be secured to thebase portion by suitable guide pins or small profile screws or the likein such a manner that top portions are secured to the base portion in aphysical position so as to line up in a corresponding manner withplumbing or manifold ports in the base portion, so that a desirablevacuum may be applied to the substrate by way of the top portion.

Laser cutting is more optimally performed in accordance with embodimentsof the present invention as follows. Substrate 300 is initially producedto have probe members with conductors of the desired number, positionand shape, such as described previously. Substrate 300 is positioned onchuck 332, preferably with the circuit side facing the direction of thelaser beam; chuck 332 is positioned on, or a part of, the laserpositioning and motion system, in a predetermined manner. The opticalsystem of the laser may automatically or manually be used to locate aposition of a known feature on substrate 300, such as fiducials 305 orthe conductors formed as part of probe members 310. The laser positionaland motion system may thus have a predetermined positional reference toboth chuck 332 and substrate 300. It also should be noted that datadeterminative of the features of substrate 300, which may includefiducials 305, the conductor runs of probe members 310 and/or the trackswhere laser cutting is to be performed, preferably is provided in theform of a data file, such as a DXF (design exchange format) or othersuitable data file, preferably created as a part of the process thatproduced substrate 300.

With positional references known, fiducials 304 may be cut with thelaser. Laser cut fiducials 304 are used in order to conduct the mainlaser cutting with the circuit or conductor run side of substrate 300facing away from the laser beam. Such cutting from the back side hasbeen determined to produce more optimal cutting of the fingers of thecontact device.

Before or after fiducials 304 are formed, guide pin holes 308 also areformed by laser cutting. With the conductor run side of substrate 300facing the direction of the laser beam, guide pin holes 308 overlayguide pin cutting holes 328 of chuck 332. The ultimate position of guidepin holes 308 vis-a-vis guide pin holes 330 of chuck 332, illustrated bydotted line holes 306, will correspond in a desired manner whensubstrate 300 is flipped over and re-positioned on chuck 332. Aspreviously expanded, with the guide pin cutting holes offset from theguide pin holes in a consistent directional manner, guide pin holes 308may be laser cut with the conductor run side of substrate 300 facing thelaser beam direction (and with guide pin holes 308 of substrate 300overlying guide pin cutting holes 328 of chuck 332), and thereaftersubstrate 300 may be flipped over and repositioned on chuck 332 so thatguide pin holes 308 of substrate 300 overlay guide pin holes 330 ofchuck 332, and thus the position of substrate 300, with the conductorrun side now facing away from the direction of the laser beam, may besecured on chuck 332 in a predetermined manner with guide pins. Itshould be noted that one of guide pin holes 308 of substrate 300 ispreferably formed as a slightly elongated hole or slot. This will enablesome minimal movement of substrate 300 vis-a-vis chuck 332 in order toaccommodate thermal coefficient of expansion mismatches between thechuck 332 and substrate 300.

As previously described, DXF or other suitable data files preferably areprovided to the laser positional and motion system. With substrate 300positioned on chuck 332, conductor run side facing away from thedirection of the laser beam, laser cutting may proceed. It should benoted that fiducials 304 previously cut with the laser are visible tothe laser optical system when substrate 300 is positioned on chuck 332with the conductor runs facing away from the direction of the laserbeam, thereby serving as an automatic or manual aid to the alignment ofthe laser positional and motion system to the desired cutting tracks onsubstrate 300. With the laser cutting tracks input by a suitable datafile to the laser system, the laser may desirably cut the fingers andoutline of probe members 310 in a more accurate and optimum manner.

Preferred methods of cutting the fingers and outlines of probe members310 will now be described with reference to FIGS. 15A and 15B. FIG. 15Aillustrates a preferred area map for laser cutting of one illustrativeprobe member 346. The laser preferably cuts “stitched” perimeter cuts341, with some material 340 remaining between stitch cuts 341. Stitchcuts 341 generally define the outline of probe member 346, with materialremaining in order to provide support to probe member 346 during theremaining laser cutting processes. It should be noted that all lasercutting of probe member 346 preferably overlays open areas orindentations 326 on chuck 332, as previously described.

In the conductor run tip portion of probe member 346, area 342 is cut inorder to provide a suitable laser track for cutting the fingers of probemember 346, as will be explained further hereinafter. In addition, guidepin holes 312 also are preferably cut in probe member 346, with guidepin holes 312 (one of which preferably is elongated), available to serveas physical positional references for probe member 346 in a finalcontact device (assuming that the final contact device is mechanicallyconstructed to take advantage of such guide pin holes). The positionallocation of guide pin holes 312 preferably is provided by the same datafile that provides the positional data for the laser cutting tracks.

FIG. 15B illustrates preferred embodiments of laser cutting methods inaccordance with the present invention. A plurality of laser cuttingtracks 345 are illustrated. Preferably, the laser is directed at firstend 344A of a laser track 345, which is positioned in the open area 342previously cut by the laser. This enables the early laser pulses, whichmay be less stable, to be directed at an open area and not at thesensitive finger portion of probe member 346. Thereafter, the laserpositioning and motion systems steps the laser towards second end 344Bof the laser track. Preferably, laser cutting along tracks 345 proceedsfrom first 344A to second end 344B, but not in the opposite direction.It has been determined that a cut from end 344A to 344B and a return cutfrom 344B to 344A may impart an excess of laser energy at the portion ofthe laser track at end 344B, which may result in an enlarged or“keyhole” type opening at end 344B, which may undesirably weaken thefinger portion of probe member 346 at this location. Alternatively, suchreturn cuts may be performed with a return cut from end 344B to end344A, but with the laser energy (either pulse rate or energy density)reduced near end 344B to avoid an enlarged keyhole type opening. Lasercutting from 344A to 344B proceeds until the entire thickness ofsubstrate 300 is traversed.

In certain preferred embodiments, each of the fingers of the tip portionof probe member 346 is cut with the laser until the cut is all of theway through the material of substrate 300. In other preferredembodiments, a single pass (or other predetermined number of passes)from 344A to 344B for a finger is made and then stepped to the adjacentfinger along the length of the tip portion. Without being bound bytheory, stepping from finger to finger may allow heat to dissipate moreoptimally as compared to repeated cutting on the same finger until thecut is complete.

It should be noted that chuck 332 in conjunction with substrate 300 maybe advantageously utilized in accordance with embodiments of the presentinvention to produce suitably fine and accurate slitting for probemembers. Chuck 332 serves to provide a desirous pull down vacuum close,such as within 0.030 inches, to where most of the laser cutting occurs,while enabling laser cutting to occur over open indentations 326 ofchuck 332. This enables the material of substrate 300 to be maintainedin a more desirous flat condition on chuck 332 during laser cutting withvacuum pull-down, while allowing dross and debris of the laser cuttingto fall into an open area of chuck 332. It also should be noted that themachining to produce chuck 332 may desirably be conducted by a CAD/CAMsystem, with the positional and other reference data for the CAD/CAMsystem for producing chuck 332 generated as a part of, or in anautomated step subsequent to, the design process that created the datafor probe members 310 of substrate 300.

Also in accordance with preferred embodiments of the present invention,lasers are used with particular properties that have been determined tobe particularly useful for making contact devices as disclosed herein.In accordance with such preferred embodiments, the laser is selected andcontrolled to provide energy of a wavelength less than about 400 nm.While YAG lasers have been applied in a variety of applications, it hasbeen determined that a Nd:YAG laser operating at the fourth harmonic, orabout 266 nm, provides particularly good results, particularly whenapplied with a pulse duration of less than, or about 25 nanoseconds, andpreferably between about 15-25 nanoseconds, with energy per pulse ofabout 200 microjoules, at a laser pulse rate of about 1000 Hz, orbetween 500 and 2000 Hz, or between 750 and 1500 Hz, and more preferablybetween 800 and 1200 Hz. With materials and other parameters selected inaccordance with embodiments of the present invention, a cutting velocityof about 5 mm/second has been determined to provide desirable results.

Additional laser cutting parameters and methodologies determined to beparticularly advantageous in accordance with additional preferredembodiments of the present invention will now be described.

As for wavelength, wavelengths shorter than 400 nm have been determinedto be preferable in such certain preferred embodiments. Longerwavelengths have been determined to in general produce more burning andless ablation. In addition, the heat affected zone (HAZ) tends to belarger to the point of damaging material necessary for the probemechanical properties and electrical properties to perform in thedesired manner. On the other hand, wavelengths much longer than 200 nmalso may be undesirable. Shorter wavelengths are believed to typicallynot contain enough energy to do the necessary ablation in order toproduce slitting.

As for pulse width, in such certain preferred embodiments pulse widthsare controlled to be shorter than 30 nanoseconds. Longer pulse widthstend to either contain more energy than the material can dissipate andnegatively affect the HAZ, or if the energy is reduced, there may beinsufficient peak power to cause ablation. Pulse widths longer than 5nanoseconds are preferably used in such embodiments. Shorter pulsewidths typically do not contain enough energy to cause ablation, orablate at such a slow rate as to become inefficient.

As for velocity, velocities faster than ¼ of the laser beam diameter perpulse is preferably used in such embodiments. Slower velocities tend toincrease the energy absorbed per unit area to the point that the HAZbecomes large enough to negatively impact the mechanical and electricalproperties of the probe member. Velocities preferably are controlled tobe slower than 1 beam diameter per pulse. Faster pulse rates arebelieved to leave material between pulse hits that do not see energy anddo not produce proper slit formation.

As for energy per pulse, in such embodiments the energy per pulsepreferably is more than about 25 micro-joules. Lower energies per pulseare believed not to contain enough energy to cause sufficient ablationfor effective slit production. In such embodiments, the energy per pulsepreferably is controlled to be less than 300 micro-joules. Higherenergies tend to not be absorbed by the material without increasing theHAZ so that it becomes large enough to negatively impact the mechanicaland electrical properties of the probe member.

As for pulse rate, in such embodiments the pulse rate preferably iscontrolled to be faster than 500 Hertz. Slower pulse rates have beendetermined to reduce the production rate of the laser system to thepoint that the slitting process becomes overly expensive. On the otherhand, in such embodiments that pulse rate preferably also is controlledto be slower than 2000 Hertz. Faster pulse rates are believed to eithernot contain enough energy per pulse to effectively ablate material orthey exceed the material's capacity to remove heat to the point that theHAZ becomes large enough to negatively impact the mechanical andelectrical properties of the probe member.

In accordance with preferred embodiments of the present invention, slitwidth also may be desirably controlled. In such preferred embodiments,the maximum slit width is controlled to be about 10 microns, as widerslit widths have been determined to consume significant area and limitthe pitch of the probe member to approximately 100 microns due the needfor area to allow for HAZ, position errors, signal path, etc. On theother hand, in such preferred embodiments the minimum slit width iscontrolled to be about 1 micron. Narrower slit widths have beendetermined to cause increased risk of undesirable bridging andmechanical crosstalk due to contact between adjacent probe fingers.

An additional improvement to laser cutting methodologies in accordancewith certain preferred embodiments of the present invention will bedescribed with reference to FIG. 16.

FIG. 16 illustrates laser beam 360 being directed onto probe member 354,such as for cutting slits between finger, such as described elsewhereherein. In this embodiment, probe member 354 is positioned on chuck 352,which is positioned on elevation mechanism 350, which may be considereda “Z dimension” stage. Laser beam 360 is focused more towards a point bylens 358 to produce focused beam 356. With the minimum spot size ingeneral being a fixed length from lens 358, in this embodiment a cuttingpass (or passes) is made in a particular area of probe member 354. Asthe cut becomes deeper, elevation mechanism 350 adjusts chuck 352 andprobe member 354 upwards. As a result of the upward movement of probemember 354, the material that is to be cut by a subsequent pass offocused laser beam 356 may once again be with a more minimal beam size.Without such upward movement, the beam becomes in effect over-focused asthe cut becomes deeper, leading to a less focused and undesirably widerspot size, which makes it difficult to achieve fine slitting.

With such embodiments, the laser beam is more focused into a spot suchthat the energy density is high enough to change the material of theprobe member into a form in which it is removed from the probe member,leaving the desired material intact. As the beam spot size is asignificant contributor to the kerf width of the material removed,dynamically adjusting the position of the probe member to maintain amore focused beam at the point of beam impact can significantly reducethe kerf width. In other embodiments, the position of the probe memberis maintained constant, while the position of lens 358 is adjusted. Whatis important is that the relative position of lens 358 and probe member354 is adjusted (dynamically) during a cutting pass, or between cuttingpasses, so that only a highly focused and small laser beam spot impingesupon the material to be removed.

Additional improvements and advantages of contact devices and probes inaccordance with embodiments of the present invention will now bedescribed.

Referring now to FIGS. 17 and 18, certain additional preferredembodiments of laser cutting in accordance with the present inventionwill now be described. As illustrated in FIG. 17, laser cutting may beperformed in two phases, each of which may be conducted in one or moreseparate passes. Two fingers of probe member 370 are illustrated fordiscussion purposes. Each finger of probe member 370 includes conductivelower layer 371, on which is formed dielectric layer 372 and conductorruns 375 having contact bumps 374. The structure of and method offorming the fingers of probe member 370 may be as described elsewhereherein.

In this embodiment, laser cutting is first conducted from the back sideof probe member 370, or the side opposite the side on which conductorruns 375 are formed. Laser cutting proceeds with one or more passes witha less controlled width, such as width X₂ as illustrated. The lasercutting of this phase may be a rougher, higher energy and perhaps fastercut phase. With the cutting being conducted from the back side, controlof the cut is less important. The cutting of this first phase goes to adepth less than the thickness of conductive lower layer 371, which beachieved by way of measuring the depth of the cut or by experimentationwith particular laser parameters and materials. What is important isthat the first phase of laser cutting be conducted from the back side ofprobe member 370 and not completely cut through the finger.

In a second phase, the laser cutting is now conducted from the frontside of probe member 370 (or the side on which conductor runs 375 areformed), with a highly focused, high energy and relatively small beamspot. Preferably, the cutting from the front side of probe member 370 isachieved with a side pass that completes the cutting through the probemember. Preferably, the front side cut has a smaller width, illustratedas width X₁. With the cutting from the front side occurring in a singleor very few passes, the amount of debris or dross depositing on thefront side of probe member 370 may be minimized.

FIG. 18 illustrates a refinement of the two step laser cutting approachdiscussed in connection with FIG. 17. In the embodiment of FIG. 18,probe member 373 includes layer 376 formed on conductive lower layer371. Dielectric layer 372 is formed on layer 376, and conductor runs 375having contact bumps 374 are formed on dielectric layer 372. Theconstituent materials of layer 376 are selected based on the particularlaser that is selected for the cutting operation. Layer 376 preferablyis highly reflective or otherwise non-absorbing of the laser beam, andserves as an “etch stop” or inhibiting layer to ensure that the firstphase, back side laser cutting does not cut entirely through probemember 373. In the second phase laser cutting, again conducted from thefront side of probe member 373, the laser cutting is again conductedwith a highly focused, high energy and relatively small beam spot.Preferably, the cutting from the front side of probe member 370 isachieved with a single pass that completes the cutting through the probemember. Preferably, the front side cut has a smaller width than the backside cut, as discussed in connection with FIG. 17. The front side cutmay be conducted with a laser beam of different parameters in order tomore readily remove the material of layer 376, etc. As before, with thecutting from the front side occurring all in a single or very fewpasses, the amount of debris or dross depositing on the front side ofprobe member 373 may be minimized.

Probe members in accordance with the present invention may be formedwith very small width and fine pitch. As a result, improved contactprobe structures may be achieved.

Referring to FIG. 19, a portion of electronic device 380 is illustratedhaving contact pads 382 and 384. Preferably electronic device 380 hascontact pads of two different sizes, illustrated as dimensions Y₁, andY₂. Due to the ability to make very fine pitch devices, such as deviceswith fingers on a 40 or below 40 micron pitch, with slits of about 2 orabout 1-3 microns, it is possible to have additional test only contactpads positioned on electronic device 380 that are small and consumelittle surface area. Larger contact pads such as pads 382 also may beprobed with the contact device, with the larger contact pads alsoserving as bonding pads (the larger area of pads 382 provide sufficientarea for wire or other bonding in the device packaging process). Smallerpads 384 are provided only for testing purposes and may be of a size notsuitable for serving as a bonding pad. Such additional probe-test-onlypads, more test contact points may be provided, which may serve toprovide parallel or otherwise more efficient testing of electronicdevice 380.

Referring now to FIGS. 20 and 21, additional embodiments of the presentinvention will be described. As illustrated, electronic device 397,which may be a high density memory device such as a 64M DRAM, isprovided to have two rows of bonding or contact pads 399 positioned in acenter portion of electronic device 397. Such a device structure may bewhat is known as a lead-on-chip (or LOC) configuration, with a leadframe (not expressly shown) secured to a front face of electronic device397 with, for example, an insulative adhesive, with bonding wiresextending from pads 399 to connection points of the lead frame.

In wafer probing of such a device, as illustrated in FIG. 20, fingers390 of the contact device may include two contact bumps, front bump 392and back bump 394, and two conductor runs 396 and 398. As illustrated,conductor runs 396 and 398 proceed substantially in parallel down thelength of finger 390, with conductor run 396 extending around backcontact bump 394 in order to make electrical contact to contact bump392. With such a contact device structure, a single finger may contact apair of the contact pads illustrated in FIG. 21. It is possible toextend this concept to three, four or more contacts and conductor runsper finger, with the contacts three in a row, or a two-by-two array,etc.

In addition, contact devices of this structure may be extended toprobing multiple electronic devices 397 with a single contact device391, as illustrated in FIG. 22. As illustrated, contact device 391 has aplurality of fingers 390 arranged in a manner to contact multipleelectronic devices 397. As with the contact device of FIG. 20, ifelectronic devices 397 include two rows of contact pads 399, thenfingers 390 may include two contact bumps. In such a manner, a singlecontact device 391 may be used to wafer probe a plurality (e.g., 4, 8,16, etc.) of electronic devices 397. It should be understood that theembodiment of FIG. 22 may include the ability to wafer test electronicdevices 397 having a single row of contact pads 399, or two rows ofcontact pads 399 (such as illustrated in FIG. 21), or three or four rowsof contact pads 399, with fingers 390 having a suitable correspondingnumber of contact pads and conductor runs. Still alternatively, twocontact devices may be provided to probe devices 397 from oppositesides, with each contact device probing one, two, three, four, etc. rowsof contact pads on the electronic devices.

Referring now to FIG. 23, an improved structure of a contact device offine pitch will now be described. As illustrated, a portion of contactdevice 400 includes a plurality of fingers 402, on which are formedconductor runs 404, each of which has a contact bump 406 formed on acontact end thereof. Contact device 400 may be formed in a manner asdescribed elsewhere herein. In this preferred embodiment, contact device400 is formed to have at least two distinct regions, controlledimpedance region 410 and stub region 408.

Unlike conventional approaches in which it is desired to maintain acontrolled impedance to the contact point for optimum signal propagationcharacteristics, this embodiment compromises the signal propagationcharacteristics in stubb region 408, while maintaining a desiredcontrolled impedance in controlled impedance region 410. As anillustrative example, the controlled impedance may be desirably 50 ohms.Controlling the 50 ohm signal environment the entire length of fingers402, however, will impose a limit on how fine a pitch may be achieved.Deviating from the 50 ohm environment in stubb region 408 may enablemore area for slitting between fingers 402 as illustrated, therebyenabling finer pitch contact devices.

It should be noted that stubb region 408 desirably is limited tosubstantially less than the wavelength of any signals of interest. Forexample, the length of stubb region 408 should be less than about ¼ or ⅛of the wavelength of the highest frequency signals of interest, and morepreferably less than about 1/10 of the wavelength of the highestfrequency signals of interest. As illustrated, with the conductor runnarrowed only in the limited length of the stubb region (e.g., about0.050 inches or less), fine pitch contact devices with suitablefrequency transmission characteristics may be desirably achieved.

It should be noted that the embodiment of FIG. 23 may be applied to bothmicrostrip or stripline configurations.

Still further improved contact device structures in accordance withother preferred embodiments of the present invention will be describedwith reference to FIGS. 24A to 24C.

It has been determined that certain contact devices exhibit non-uniformscrub characteristics. As a for example, certain contact devices tend toexhibit less scrub for the fingers at the ends of the row of fingers. Itin general is desirable to have more uniform scrub characteristics forall of the fingers of the row of fingers.

In FIG. 24A, a contact device having non-uniform slit lengths isprovided. As illustrated, contact device 412, which preferably includesmechanical ground 414 such as previously described, includes a pluralityof fingers in the tip region 416. As illustrated, fingers near the endof the rows of fingers have a different slit length from slits betweenfingers in the center portion of the row of fingers. Preferably, fingersnear the end of the row have a slit, such as slit 418, that is shorterthan the slits between fingers in the center portion, such as slit 420.With slits near the end of the row of a different (preferably shorter)length, a more uniform scrub characteristic may be obtained in certainembodiments.

In FIG. 24B, a contact device having a varying or non-uniform mechanicalground 424 is provided. As illustrated, contact device 422 includesmechanical ground 424 with extending portions near the end region 430adjacent to the end of the row of fingers. In this embodiment, fingers428 in the tip region 426 of contact device 422 may be of the samelength, while a non-uniform mechanical ground alters the stress sharingcharacteristics of the fingers near the end of the row of fingers ascompared to fingers in the center portion of the row of fingers.Preferably, mechanical ground 424 provides a mechanical ground contactpoint nearer the base of fingers 428 for those fingers located near theend of the row of fingers. Still preferably, the mechanical ground maybe provided in a manner to gradually vary from the end region 430 ofmechanical ground 424 to a center portion of the mechanical ground. Witha varying or non-uniform mechanical ground, a more uniform scrubcharacteristic may be obtained in certain embodiments.

In FIG. 24C, a contact device having a varying or non-uniform fingerwidth is provided. As illustrated, contact device 432 includesmechanical ground 434 and a plurality of fingers (e.g., fingers 436 and438). Fingers near the end of the row of fingers (e.g., finger 436) isof a width greater than a finger near the center portion of the row offingers (e.g., finger 438). With a varying or non-uniform finger width,a more uniform scrub characteristic may be obtained in certainembodiments.

Further improved contact probe structures in accordance with additionalpreferred embodiments of the present invention will now be describedwith reference to FIGS. 25A to 25D. As illustrated in these embodiments,two (and perhaps more than two) contact bumps 446 and conductor runs 444are provided for each finger 441. Conductor runs 444 are provided ondielectric 442, which is formed on conductor layer 440, such as in amanner described elsewhere herein.

In the illustrated embodiments, one or more partial slits 448 areprovided in the back side opposite the side where conductor runs 444 areformed. When multiple conductor runs are formed on a single finger, thefingers, being torsionally stiff, may not be sufficiently compliant toaccommodate height variations that may be encountered between contactpads of the electronic device to be tested. Through micromachining suchas with a laser, partial slits may be formed in the back side of thefingers to increase the torsional compliance.

FIG. 25A illustrates compliance slit 448 extending substantially inparallel to the length of finger 441. The arrow indicates a torsionalmoment created during an exemplary non-uniform contact. FIG. 25Billustrates compliance slit 448 having two portions, each extending froma center portion of the end of finger 441 to a point along the length offinger 441. FIG. 25C illustrates compliance slit 448 having two curvedportions, each extending from a center portion of the end of finger 441to a point along the length of finger 441. FIG. 25D illustratescompliance slit 448 extending initially in parallel to the length offinger 441 for a predetermined length, and then perpendicularly to thelength of finger 441 in the shape of a “T.” With such compliance slits,a contact device with two or more contact bumps and conductor runs perfinger with improved compliance may be obtained.

Still other improved methods of producing contact devices, and improvedmethods of producing electronic devices using such contact devices, willnow be described.

In accordance with contact devices as described elsewhere herein, andalso with techniques known as probe cards, using fine needles or wires,membrane contact devices utilizing a membrane having conductors andconnection points on a membrane which typically is pulled down over anelastomer (e.g., a truncated pyramid) (such as produced by CascadeMicrotech Inc.) and then contacted with the DUT and other contactdevices such contacts appended to microsprings/bonding wires (such asproduced by Formfactor, Inc.), construction of such contact devicestypically has been way of separate construction based on physical dataprovided in physical form (e.g., written or electronic numbers such asphysical coordinates, etc.), which are then using to construct thecontact device. Such a manner of manufacturing contact devices hasdisadvantages, such as requiring excessive manual intervention, forexample manual entry of contact location and the like into a tool formachining or otherwise fabricating the contact device. Such techniquesare inefficient to some degree and enable the introduction of errors andthe like, and improved methods are desirable for both the end devicemanufacturer and the manufacturer of the contact device. In addition,many such conventional techniques have been limited in that theconductors for the contact device are offered in a single or limited setof electrical characteristics (e.g., all needles having in effect thesame size and overall electrical characteristics, etc.), when in realityconductors for the contact device more desirably would have electricalor physical characteristics more correspondingly optimized vis-a-vis theelectronic device being tested.

The present invention provides methods for manufacturing such contactdevices for making connection to an electronic circuit device andmethods of using the same in the production of integrated circuits,liquid crystal displays or other electronic devices. In accordance withthe present invention, the manufacturing of the contact device and theelectronic device is more tightly integrated, thereby enabling moreefficient manufacturing of the contact device, and thereby enabling moreeffective input by the electronic device designer/manufacturer intoproperties of the contact device, and smaller and more highly integratedelectronic devices.

For purposes of understanding the present invention, it should be notedthat, as device and pin/bonding pad geometries and dimensions of theelectronic device become increasingly finer, leading, for example, tofiner pitches and spacings, the physical area or real estate,particularly near the probe tip/finger areas (particularly with astructure such as disclosed in U.S. Pat. No. 5,621,333) becomesincreasingly critical. It should be noted that the electronic devicedesigner/manufacturer must try to achieve the greatest density possible,which thus leads to the smallest possible devices and/or the smallestpossible pad spacings, which in turns controls the width of, andavailable area/real estate in, the probe tip/finger areas. In general,this trend has led to smaller probe tips/fingers, and finer conductorruns in these areas.

Unfortunately, however, this tends to compromise the contact device orprobe performance in certain respects, as smaller conductor runs maylead to undesirable electrical characteristics. For example, conductorruns that are too narrow may result in increased resistance/impedance orheating, or simply an inability to carry the desired or required currentlevel. Other leads, for example, may have minimal current or signalperformance requirements. Thus, it may be desirable to have a widerconductor for power or ground leads, for example, even if this resultsin smaller conductors for other leads. It also may be desirable incertain applications to tailor the conductor runs for certain fingers tohave a greater or lesser width, while adjusting the widths of otherconductors accordingly. Other conductors, for example, may have minimalor maximal conductor widths and/or spacings due to the characteristicsof the signals to be carried on such conductors. As physical areabecomes more constrained, in general it can become important thatconductors be arranged near the probe tip/finger areas in ways (in termsof size, spacing, etc.), that optimize the desired electricalcharacteristics.

In accordance with the present invention, such electronic devices,including those with electrical or physical characteristics of thecontact device conductors selected or optimized by the designer ormanufacturer of the electronic device, may be produced in a moreoptimized and efficient manner. It should be understood that the presentinvention is particularly well suited to produce contact devices orprobes such as is disclosed in U.S. Pat. No. 5,621,333 and for theproduction of electronic devices such as integrated circuits, liquidcrystal or other displays and other devices using contact devices havingelectrical contact points that are produced using photolithographic orother automated design and/or manufacturing techniques, although certaintechniques of the present invention may be extended to other types ofcontact or probe devices, such as those described above.

In accordance with the present invention, more automated production ofcontact or probe devices, in whole or part, is implemented as part ofthe design process for the electronic device. In accordance with thepresent invention, physical characteristics of the contact device, suchas physical size or geometry and the location and size of contactpoints, are specified as part of the electronic devicedesign/manufacturing process. Through data entry or selection of contactdevice options presented to one or more designers of the electronicdevice, characteristics of the contact device are specified as part ofthe electronic device design/manufacturing process. Thereafter, datagenerated as part of the electronic device design/manufacturing processis provided to an automated tool for layout and/or manufacture of thecontact device.

More preferably, the designer of the electronic device has the option tospecify or select desired electrical characteristics of particularconductors on the contact device. In accordance with the presentinvention, the physical layout, including size, position and/or lengthof the fingers or conductors of the contact device or probe, may be moreautomatically generated. With probe or contact devices such as disclosedin U.S. Pat. No. 5,621,333 and the like, such a process may enableproduction of masks or patterns (such an electron beam or opticalwriting device) to generate the probe or contact device as a result ofsoftware processing of data generated by the electronic device designprocess. In particular, probes or contact devices having conductorcharacteristics, either physical or electrical, specified or selected bya designer of the electronic device may be more efficiently generated ina more automated manner, thereby enabling the ultimate manufacture ofthe electronic devices in a more efficient or optimized manner.

Referring to FIG. 26A, a general design flow in accordance with certainpreferred embodiments of the present invention is illustrated. At step450, the device (e.g., integrated circuit, display or other electronicdevice having bonding pads or other conductor attachment points, etc.)is designed at a high level, as indicated by the box HLD, for high leveldesign. The HLD step may be conducted using conventional-type electronicdesign tools. For example, at step 450 a designer may define desiredinput and output characteristics of the device being designed, and maydetermine various transfer function, logic or other electrical or signalcharacteristics of the device. For example, such design may beaccomplished using VHDL, behavioral models or other analog and/ordigital design characteristics. As a part of such HLD process, library452 may be accessed. Library 452 may contain various libraries ofcircuit elements, modules or other design data to facilitate the HLD ofthe electronic device. In certain preferred embodiments, library 452 maycontain or be able to access elements specifying physical or electricalcharacteristics or options available for contact points or conductorruns of the contact device.

Device fabrication is performed at step 454, it being understood thatadditional design verification steps may have occurred between step 450and step 454 as part of the overall electronic device design process.For example, high level designs typically undergo simulation, layout,re-simulation and other design verification steps in order to debug tothe extent possible the design of the electronic device prior toexpending the resources for device fabrication. All such design stepsare contemplated by the design flow of FIG. 26A. After devicefabrication step 454, the devices, typically in wafer form, proceed tostep 464 for probe testing.

A parallel design flow for contact device preparation is illustrated inFIG. 26A and is an important aspect of certain preferred embodiments ofthe present invention. As illustrated, the HLD design step 450 alsoentails generation of data suitable for use in design/fabricating thecontact device. In certain preferred embodiments, at a HLD stage adesigner may specify physical or electrical characteristics of thecontact device. As illustrative examples, the designer may specify (orselect, etc.) that certain contacts of the electronic device are powersupply lines, non-critical level sensitive lines (such as chip select orstatus lines), or high frequency or frequency critical lines, etc. Ascertain contact devices as contemplated by the present invention enablethe conductors and contacts to be more precisely tailored for theparticular desired characteristics, having such characteristicsselectable by a designer at a higher level point in the electronicdevice design cycle will enable more automated design tools to, forexample, layout and map the conductors of the contact device. As forexample, high frequency lines may be mapped to preserve a controlledimpedance environment to a high degree, while power supply and/or groundconductors may be arranged or mapped to provide a larger currentcarrying capacity. Non-critical lines may be mapped in a less critical(e.g., smaller conductor form) manner in order to minimize area usage incritical areas. In addition, certain devices may specify an externalimpedance, such as a decoupling capacitor at a point close to thecontact pads of the contact device (as described elsewhere herein). Withsuch an automated design flow as illustrated in FIG. 26A, at a higherlevel point in the design cycle data specifying such an externalimpedance may be presented to tools for laying out and mapping theconductors of the contact device.

At step 456, a tool for generating and/or processing test pad or otherdata specifying or identifying characteristics of the contact points ofthe electronic device is utilized. Such a step may entail extractingcontact point physical or electrical characteristics data correspondingto the electronic device, but preferably the tools of the HLD step forthe electronic device present data specifying relevant desired physicaland/or electrical characteristics of the contact device. What isimportant is that such data for purposes of preparing the contact devicebe made available, preferably in a more automated manner, to the designand fabrication flow for the contact device.

At step 458, a contact device tool lays out and/or maps conductors ofthe contact device. Such a tool preferably contemplates the type oftester or testers to be used to test the electronic device, and alsomakes use of any physical and/or electrical data specified or selectedby the HLD process for the electronic device. With such a design flow,preparation of the contact device, including reflecting design datainput from the electronic device design process, may be more readilyconducted. With such a design flow, particular conductors of the contactdevice may be more readily tailored for the particular desired physicaland/or electrical characteristics, preferably as specified or selectedas part of the electronic device design process.

At step 460, based on data generated at step 458, the contact device isprepared. As illustrative examples, by way of steps 458 and 460, alayout and mapping of the conductors of the contact device is made, andphotolithographic or similar masks are more automatically prepared orgenerated (such as by way of a mask shop) in order for the contactdevice to be prepared (illustrative steps to prepare such a contactdevice are described elsewhere herein).

As previously described, certain preferred fabrication processes of thecontact device involve laser cutting with a chuck prepared for the lasercutting step. In an alternative design flow embodiment, data generatedat step 458 for the contact device is more automatically generated in aform suitable for preparation of the chuck. As previously described, aDXF or other suitable data format file may be created in order tofacilitate the machining or other preparation of a chuck or otherimplement for producing the contact device (e.g., a fine pitch, fineslit contact device, for which precise laser cutting is desired, etc.).

At step 460, the contact device is fabricated. At step 464, probetesting of the electronic devices may be accomplished, preferably at awafer, unpackaged level. Tested devices may be rejected and identifiedas rejected (such as by inking or tracking with a computer), andelectronic devices passing the probe testing step may proceed to devicepackaging step 466. At step 466, the wafers may be diced into chips, forexample, with chips encapsulated and packaged, such as with wirebonding, etc., and packaged in a resin or ceramic or other package.Thereafter, packaged devices may undergo additional testing at step 468,with the device either rejected or accepted. Accepted devices may thenbe prepared for use in a system design, prepared for inventorying,shipment, sales, etc.

Referring to FIG. 26B, exemplary data format 470 is illustrated. Tofacilitate the design flow depicted in FIG. 26B for the contact device,at step 450 and/or step 456 (or other suitable point in the contactdevice design flow), electronically stored parameters for the contactpoints of the contact device are generated and/or processed. Asillustrative examples, coordinate-type location data for particularcontact points may be provided, along with a unique identifier or namefor the pad or contact point. Preferably, pad or contact data isprovided, which may specify the type of signals to be transmittedthrough the pad (e.g., power supply or ground, high frequency signaltransmission, etc.) and/or other suitable data by which particularphysical or electrical characteristics of the contact point of thecontact device may be determined. Such pad data may be generated as aresult of a designer of the electronic device specifying or selectingoptions presented as a part or, or in conjunction with, HLD step 450.Still preferably, in certain embodiments tester channel or othersuitable data identifying channels or other characteristics of thetester to be used to test the electronic device is provided.

The format of FIG. 26B is exemplary only; what is important is that thedesign flow of the electronic device contemplate the design flow of thecontact device, and present data to the contact device design flow in asuitable and more automated electronic format. Preferably, a personinvolved in the HLD process of the electronic device specify or selectparameters of the contact device, so that conductors of the contactdevice may be laid out or mapped based on the desired physical and/orelectrical characteristics of the particular conductors, which mayinclude laying out the contact device so that external impedances may beprovided at a desirable point on the contact device (e.g., a decouplingcapacitor or other external impedance at a point close to which thecontact device contacts the electronic device, etc.).

In accordance with such embodiments, improved processes formanufacturing electronic devices may be developed. For example, methodsin accordance with such embodiments may include the steps of: generatinga design description of the electronic device using a computer aideddesign tool; electronically determining physical device datarepresenting a physical description of the electronic device based onthe design description, wherein the physical device data includes datadefining connection points for connecting the electronic device toexternal circuits; producing a physical embodiment of the electronicdevice in accordance with the physical device data; electronicallydetermining physical test member data representing conductors andcontact points of a test member for testing the electronic device;producing the test member in accordance with the test member data;engaging the test member with the electronic device, wherein contactpoints of the test member engage connection points of the electronicdevice, wherein stimulus and response instruments apply test signals tothe electronic device through the test member and receive signals fromthe electronic device, wherein the stimulus and response instrumentsdetermine whether the electronic device is defective. Refinements ofsuch methods may include: the physical device data includes dataidentifying one or more connection points of the electronic device andalso includes signal data indicative of electrical signalcharacteristics of signals to be conducted through the one or moreconnection points; the step of electronically determining physical testmember data includes determining physical characteristics of conductorsof the test member in accordance with the signal data; the width of oneor more of the conductors is determined in accordance with the signaldata; the spacing of one or more of the conductors in determined inaccordance with the signal data; the width and spacing of one or more ofthe conductors is determined in accordance with the signal data; thephysical characteristics of a first conductor is determined at a firststep, wherein the physical characteristics of a second conductor isdetermined at a second step, wherein the physical characteristics of thesecond conductor are determined based on the signal data and/or thephysical characteristics of the first conductor; the first conductor isdetermined to have a first width, wherein the second conductor isdetermined to have a second width, wherein the first width is greaterthan the second width; the conductors include one or more thirdconductors, wherein the one or more third conductors are determined tohave a third width; the third width is intermediate to the first andsecond widths; the width and spacing of the conductors is determined inaccordance with the signal data, wherein the width and spacing of theconductors is determined in an iterative manner depending upon signaldata of one or more of the conductors; and/or the width and spacing ofthe conductors is physically mapped in accordance with the signal data.

Additional preferred embodiments of the present invention in whichmultiple electronic devices, or arrays of contacts on one or moreelectronic devices, may be simultaneously probed will be described withreference to FIGS. 27 and 28.

FIG. 27 illustrates an exemplary arrangement for such multi-site orarray probing in accordance with preferred embodiments of the presentinvention. In such embodiments, multiple probe members are provided; inthe illustrative embodiment, each side includes two probe members, lowerprobe member 482 and upper probe member 486, which may be manufacturingas described elsewhere herein. Each probe member includes a plurality ofcontact bumps 494 for contact to electronic devices formed on substrate480.

As previously described, position of a suitable mechanical ground orsupport is important for proper stress sharing and/or compliance withdeviations with planarity of the contact pads on the electronic devices.In the illustrative arrangement, first mechanical support 484 isprovided between lower probe member 482 and upper probe member 486.Preferably, mechanical support 484 is glued or otherwise secured in afixed manner to the two probe members. Mechanical support 484 providessupport for lower probe member 482 when it is pushed into contact withthe electronic devices.

Mechanical support 488 is provided above upper probe member 486 and issecured to an upper surface of upper probe member, again preferably witha glue or other adhesive in a fixed manner. Mechanical support 488 iscoupled to PCB 490, preferably in a manner to be adjusted for alignmentpurposes. A three point adjustment or four point adjustment mechanismpreferably is used to adjust primarily the planarity of the contactdevice, and in particular the planarity of the contacts of the probemember, with respect to the surface of substrate 480. The conductor runson probe members 482 and 486 is electrically coupled to PCB 490 in theillustrated embodiments with flex circuits 492 or other suitableelectrical connector arrangement.

In certain preferred embodiments, each of the probe members has one, twoor perhaps more contact pads per finger (as described elsewhere herein),and preferably has fingers arranged in a line so as to probe multipleelectronic devices, or multiple rows of contacts on one more devices(e.g., a type of array probing). The size and positioning and geometriesof the probe members and mechanical support 484, as well as contactpositions, may be selected so as to properly correspond with contactpads on the electronic devices.

As an illustrative example, such a contact device configuration may beused to probe an array of electronic devices on a wafer. As illustratedin FIG. 28, wafer 500 includes a number of electronic devices 502arranged in a conventional matrix manner. Such devices may be, forexample, dynamic random access memories or other memory or othersemiconductor devices. In the illustrated arrangement, each electronicdevice 502 includes a single row of contact pads arranged down thecenter or in the interior of the electronic device (such as the LOCdevices described elsewhere herein). With the arrangement of FIG. 27,fingers on each of the probe members may span eight or some otherdesired number of electronic devices. With each probe member contactingone row of electronic devices, a four by eight array of electronicdevices may be simultaneously probed with the contact device.

As will be understood, other arrangements of electronic devices may beprobed with such a configuration, such as a four by four or other array,and also it may be used to probe an array of contacts on a singleelectronic device, or an array of contacts on a row or other multiplearrangement of electronic devices, etc.

A further preferred embodiment of a contact device incorporatingexternal impedances or other components on the probe member will now bedescribed with reference to FIG. 29.

As illustrated in FIG. 29, probe member 506 includes a number of fingers508, which may be formed in a manner as described elsewhere herein.Conductor run 510 extends back from the tip portion of the fingers, andthe conductor runs of probe member 506 are mapped to spread out so thatcomponent 512 may be electrically coupled to conductor run 510.Component 512 may be, for example, a decoupling capacitor with a firstend coupled to a power supply line, and with a second end coupled to thegrounded substrate through via 511. As an additional example, theconductor runs may be mapped to provide an area for component 514 to beformed directly onto the substrate of the probe member. As an additionalexample, component 514 may be a planar capacitor formed with a thinnerdielectric formed between the grounded substrate and an upper plate ofthe capacitor. As one additional component, a short to the groundedsubstrate may be formed by via 516 at a position on or near one or moreof fingers 508.

Resistive or inductive elements may similarly be formed on probe member506, with proper mapping of the conductor runs to provide a suitablearea for the component, and proper fabrication steps. Certain simpleexternal circuits similarly may be formed on the probe members, such asa filter or other circuit as may be desired for the particularelectronic devices.

It will be appreciated that the invention is not restricted to theparticular embodiment that has been described, and that variations maybe made therein without departing from the scope of the invention asdefined in the appended claims and equivalents thereof. For example,although the invention has been described with reference to the drawingsin terms of strip line and microstrip transmission line environments, ifthe film 14 were omitted and every other conductor run 26 across thecontact device were a ground conductor run, a combination of amicrostrip and coplanar transmission line environment would be provided.If every other conductor run were not a ground run, a microstriptransmission line environment would be provided as far as the forwardedge of the layer 44, and for some applications, it might be acceptablefor the transmission line environment to terminate at this point,provided that it is quite close to the contact bumps. Application of theinvention to a semiconductor tester has been described with reference toan implementation in which there is one contact bump on each finger ofthe contact device, and the use of individual fingers for each contactbump ensures maximum accommodation of non-coplanarity of the contactpads of the DUT. However, it might be advantageous to provide twocontact bumps, each connected to its own conductor run, since torsion ofthe finger accommodates a difference in height of the respective contactpads, and the greater width of the finger provides substantially greaterstiffness with respect to deflection. The invention is not limited totesting of devices prior to packaging and may he used for final testingof packaged devices, particularly a device that is packaged for surfacemounting, since the terminals are then suitably positioned forengagement by the contact bumps. Further, numerical references, whilegiving unexpectedly desirable results in the preferred embodiments overprior art techniques, may be adjusted in other embodiments.

Various embodiments are disclosed for illustrative purposes, which maybe utilized to produce contact devices for testing a variety ofelectronic devices, and for producing electronic devices utilizing suchcontact devices.

1. A method for manufacturing an electronic device, comprising the steps of: generating a design description of the electronic device using a computer aided design tool; electronically determining physical device data representing a physical description of the electronic device based on the design description, wherein the physical device data includes data defining connection points for connecting the electronic device to external circuits, wherein the connection points include at least a first connection point that is used for testing of the electronic device and also for electrical connection to the electronic device during operation of the electronic device and at least a second connection point that is used only for testing of the electronic device, wherein the second connection point has a physical dimension that is smaller than a corresponding physical dimension of the first connection point; producing a physical embodiment of the electronic device in accordance with the physical device data; electronically determining physical test member data representing conductors and contact points of a test member for testing the electronic device, wherein the step of electronically determining physical test member data includes determining at least a portion of a physical layout of conductors and contact points of the test member based on the data defining connection points for connecting the electronic device to external circuits; producing the test member in accordance with the test member data; engaging the test member with the electronic device, wherein contact points of the test member engage connection points of the electronic device, wherein stimulus and response instruments apply test signals to the electronic device through the test member and receive signals from the electronic device, wherein the stimulus and response instruments determine whether the electronic device is defective.
 2. The method of claim 1, wherein a first conductor is determined to have a first width, wherein a second conductor is determined to have a second width, wherein the first width is greater than the second width.
 3. The method of claim 2, wherein the conductors include one or more third conductors, wherein the one or more third conductors are determined to have a third width.
 4. The method of claim 3, wherein the third width is intermediate to the first and second widths.
 5. The method of claim 1, wherein the width and spacing of the conductors is determined in accordance with signal data corresponding to the connection points.
 6. The method of claim 5, wherein the width and spacing of the conductors is determined in an iterative manner depending upon the signal data.
 7. The method of claim 5, wherein the width and spacing of the conductors is physically mapped in accordance with the signal data.
 8. The method of claim 1, wherein the step of electronically determining physical test member data comprises generating data having a format, wherein the format includes one or more fields, wherein the one or more fields includes fields identifying each of the contact points of the test member, physical position data for each of the contact points of the test member, and/or electrical or physical characteristics data for each of the contact points of the test member.
 9. The method of claim 1, wherein the physical test member data are generated as a result of options selected by a user during the step of generating the design description of the electronic device.
 10. The method of claim 1, wherein the physical test member data include data corresponding to an external impedance to be coupled to one or more of the contact points of the test member, wherein the conductors of the physical test member are physically arranged to provide an area for coupling of the external impedance.
 11. The method of claim 10, wherein the external impedance comprises a capacitor.
 12. The method of claim 1, wherein the test member is produced using a photolithographic process.
 13. The method of claim 12, wherein the photolithographic process utilizes a mask generated from the physical test member data.
 14. The method of claim 1, wherein the electronic device comprises an integrated circuit or display device.
 15. The method of claim 1, wherein the electronic device comprises a semiconductor device.
 16. The method of claim 15, wherein the semiconductor device comprises a memory device.
 17. The method of claim 15, wherein the semiconductor device comprises a lead on chip (LOC) semiconductor device.
 18. The method of claim 1, wherein physical characteristics of one or more of the conductors carrying power supply signals are different from physical characteristics of one or more of the conductors carrying varying signals.
 19. The method of claim 1, wherein physical characteristics of one or more of the conductors carrying higher frequency signals are different from physical characteristics of one or more of the conductors carrying lower frequency signals.
 20. The method of claim 1, wherein the test member comprises a membrane test. member.
 21. The method of claim 20, wherein the membrane test member comprises a membrane having conductors and contact points.
 22. The method of claim 20, wherein the membrane is pulled over an elastomer or truncated pyramid.
 23. The method of claim 1, wherein the test member comprises microsprings.
 24. The method of claim 1, wherein the test member comprises a probe member having a proximal end and a distal end, wherein the probe member comprises a substrate having fingers projecting from the distal end of the probe member along an axis, wherein the fingers have conductors and contact points formed thereon for connection with the connection points of the electronic device.
 25. The method of claim 1, wherein the test member includes one or more rows of contact points.
 26. The method of claim 25, wherein the electronic device comprises a lead on chip (LOG) semiconductor device.
 27. The method of claim 1, wherein data corresponding to a physical layout of the electronic device is electronically produced, wherein data corresponding to a physical layout of the test member is electronically produced, wherein physical coordinate data corresponding to connection points of the electronic device are not manually entered into a software tool in order to produce the data corresponding to a physical layout of the test member. 